In the manufacture of pneumatic tires, the general practice has been to assemble the carcass components in the shape of a cylindrical band and then to apply tread rubber as the final step, or one of the final steps in the assembly process. In the case of small relatively lightweight tires, such as passenger car tires, the tread rubber can be, and often is, applied while the carcass is in the shape of an essentially cylindrical band, following which the assembled but still unvulcanized tire is expanded to approximately its final toroidal contours. A different procedure is required for large heavy tires.
Large radial tires for heavy trucks, aircraft, or off-the-road vehicles are generally built by assembling the carcass parts in some approximation to the final toroidal shape, or, if assembly in the approximate shape of a cylinder is possible and convenient, by reshaping the carcass to an approximation of its final toroidal shape before the tread rubber is applied. The application of the tread to the toroidal carcass then requires some specialized procedures and equipment.
This equipment must present the toroidal carcass to equipment for feeding tread rubber so that the rubber can be applied uniformly around the circumference of the carcass and so that satisfactory resistance to stitching pressure for uniting the tread rubber to the carcass can be provided by inflation of the tire. The equipment heretofore used for supporting large, heavy carcasses for application of treads has generally been some adaptation of the conventional tire supporting rims of vehicle wheels, or else devices which expand to grip the radially inner surface of each tire bead. The mounting and dismounting of the carcasses on such equipment has been laborious and costly, and has not always provided the precise location required for symmetrical placement of the tread rubber.
The object of this invention, accordingly, is to provide a superior, accurate and convenient construction for a temporary support for a large, heavy tire carcass permitting satisfactory precise mechanized application of tread rubber in a symmetrical position on the carcass.